A.G. Brusova, P.A. Manokhin,
T.K. Puzanovskaya, T.A. Shyshkovets
Computer Nonlinear Diagnosis (NLS) is a new highly informative method provided to examine
the spine and spinal marrow. The NLS advantages are non-invasiveness,
scalability of the image field, a capability to obtain sections of any orientation and virtual
imaging of radicular canals and paravertebral zone. Undoubtedly the use of NLS in
diagnosis of degenerative spine diseases has apparent prospects.
Subject and methods
The investigation was conducted by a 1.5 GHz NLS unit. 1217 patients affected by
degenerative changes in the lumbar region of the spine were investigated. NLS analysis of
the spine and spinal marrow was performed for all patients. 112 patients had NLS and CT,
and myelography was performed for 10 patients.
Analysis of results
In 87% of cases we found disks affected by degenerative changes. The earliest
degenerative change in inter-vertebral disks (ID) was a hyper-chromous lesion (6 points on
Flandler’s scale) in zone between the pulpous nucleus and the fibrous annulus. Along with
the degenerative changes NLS has detected an increased chromogenic density of the signal
from the bone marrow in the adjacent regions of the vertebral bodies (4-5 points according
to Flandler’s scale). 3 degrees of degenerative changes could be distinguished depending on
the process intensity.
Degree 1, a hyper-chromous zone appraised at 4-5 points on Flandler’s scale, was
detected in 90 patients. Conventional radiographs did not display any changes.
Formation of fibro-vascular tissue followed by its penetration into the bone marrow is
believed to underlie the changes. Some authors relate these changes to the lack of
stability in this segment.
The histograms displayed a spectral similarity to the reference standard “intervertebral
osteo-chondrosis” (D0.396 to 0.425).
Degree 2, a hyper-chromous response in the affected zone at 5-6 points on Flandler’s
scale was detected in 215 patients. Conventional radiographs did not show any changes.
According to some literary evidence, in this phase the histology detects a substitution of the
fat bone marrow for the red bone marrow often accompanied by enlarged trabeculae. This
phase generally precedes an osteo-chondrosis development which can be diagnosed a little
while later by conventional radiographs.
The spectral similarity was close to the reference standard “inter-vertebral
osteochondrosis” (D 0.246 to 0.360).
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Degree 3, a frank hyper-chromous response (6 points), which corresponds to a far
advanced vertebral body sclerosis, was detected in 312 patients. Some secondary
symptoms, like local bulging and vertebral asteophytes, were detected with far advanced
degenerative lesion of the disks and a substantial similarity to the reference stand
“osteochondrosis” (D from 0.152 to 0.218). NLS enables differentiation between a protrusion
and prolapse of the disk and existence of rupture of the fibrotic ring and the condition of
longitudinal and other ligaments.
A protrusion is defined as a bulging of the disk tissue beyond the posterior outline of the
vertebral body into the spinal canal. The fibrotic ring tissue endures though becomes
very thin and NLS only reveals a zone of slight destructive change in the structure (3-4
points). With compression it gives an acutely frank hyper-chromous response (6 points).
Protrusion may be accompanied by a slight caudal shift which is quite often defined by
means of the NLS-method at L5-81 inter-vertebral disk level. NLS detected protrusion in 729
patients.
The rupture of the fibriotic ring fibers results in the prolapse of the pulpous nucleus on a
subligamentary level and the ligament rupture results in the prolapse inside the
cerebrospinal canal. As can be seen from NLS, the longitudinal ligaments look well
delimited and are represented as hyper-chromous band-like structures (5-6 points) which
adjoin the bones and the fibrotic ring. The extra-ligamentary prolapse can shift either in a
caudal or a cranial direction. The extra-ligamentary prolapses of the disk that lost contact
with the host disk become sequesters. Occasionally, we observed some very small extraligamentary sequesters which shifted far into the cerebrospinal canal, which made it hard
to detect them.
The NLS-investigation detected prolapse in 445 patients. In 68% of cases the hernia of
intervertebral disk was combined with other degenerative dystrophic spinal changes on
this level. The hernia of the intervertebral disk was detected at L4-5 level in 83%, and
L5-8 level in 15% and at L3-4 level in 2% of cases. A lesion of several disks was found
in 50 patients. 196 patients underwent surgery, among them 114 had lateral hernia, 76
patients had median lateral hernia and 6 had median hernia. 5 patients had surgery for
hernia recurrence. The NLS diagnosed extraligamentary sequestrated hernia in 38
patients, and intracural hernia was diagnosed in 3 persons. Multiple sequesters were
detected in 5 patients.
The clinical symptomatology for the prolapse of intervertebral disks was variable and did not
always depend on their size. In some cases we observed median protrusions which did not
result in any clinical implications. The clinical symptomology for small
sequestrated hernia was no less than for large sequesters.
In evaluating the NLS data not only the size of hernia but also the reserve area of the
cerebrospinal canal and their prepositions should be taken into account.
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With a suspected hernia the NLS-investigation should be performed at least in two
planes, sagittal and paraxial, i.e. parallel to the disk plane, and the sagittal investigation in
T1W-SE can be combined with other sequences.
The median prolapses of intervertebral disks in sagittal shots could be seen quite clearly. The
signal content of the hernia predominantly corresponded to the NLS signal content of the
pulpous nucleus. The external part of the fibrotic ring, posterior longitudinal
ligaments and the dura matter give a frank hyperchromous response and do not
differentiate from one another. Thus, the NLS-method sometimes fails to present a direct
proof of a rupture in the external part of the fibrotic ring.
It is largely a lesion of the pulpous nucleus on the side of the back edge of the vertebral
body that speaks in favor of the protrusion in axial shots. Displacements and
compression of the spinal marrow can well be seen in both sagittal and axial projections.
Sagittal shots have an advantage in deciding on the disk prolapse, the size of
intervertebral foramina and the condition of the cerebrospinal canal and bones. These
shots are not significant for detecting an intra-dural process with the cone especially
poorly visible in them. Frontal shots have drawbacks in determining the condition of the
pulpus nucleus and fibrotic ring. To that end paraxial virtual models are used, allowing to
differentiate the process between the pulpus nucleus and the fibrotic ring and
sometimes make it possible to differentiate between the fibrotic ring rupture and the
protrusion free of the rupture. Thanks to virtual dimensional scaling sagittal shots allow to
well delimit the subarachnoid space.